Controlled temperature gradient vapor-generator



July 20, 1965 R. s. MlKscH ETAL 3,195,514

CONTROLLED TEMPERATURE GRADIENT VAPOR-GENERATOR Filed Sept. 5, 1961 2 Sheets-Sheet 1 EVA/20H4 70E -51//752//64729 mme efe/am F1- gai July 20, 1965 R, s, MlKscH ETAL 3,195,514

CONTROLLED TEMPERATURE GRADIENT VAPOR-GENERATOR INVENTORS: @MSSELL .5. M/KSCH 2056.27' E. CORR/@AN lax/@ United States Patent 3,195,514 CGNTRLLED TEMPERATURE GRADIENT VAPR-GENERATOR Russeil S. Milisch, Redwood ity, and Robert E. Cori-iden, Los Altos, Calif., assignors to American Radiator & Standard Sanitary Corporation, New York, NY., a corporation of Delaware Filed Sept. 5, 196i, Ser. No. 136,076 6 Claims. (Cl. 122-4) This invention relates to` and in general has for its object the provision of a vapor-generator for supplying vapor to any desired equipment such as, for example, the jet of an attitude deviation correction motor of a space vehicle.

Itis essential that generators for this purpose be compact, of low weight, and mechanically simple.

More specically, one of the objects of this invention is the provision of a generator of the character above described, independent of the existence or action of gravity, and including: a reservoir containing a liquid and its vapor in two-phase equilibrium with each other; an evaporator-superheater connected to the reservoir through a restricted connector and provided with a valved outlet; and means for maintaining the temperatures in the reservoir and the evaporator-superheater such that the temperature in .the latter is higher than that in the reservoir and that pressures in the two are substantially equal to each other when the valved outlet is closed and are higher than downstream pressure when the valve is open. ln such a system, dry vapor will always be available at the valved outlet at a pressure greater than the ambient pressure, and when the outlet is opened in response to a demand signal vapor will low through the outlet under the influence of the existing differential pressure. The iiow of vapor out of the system reduces the pressure within the superheater, this reduces the pressure and increases the vapor volume within the generator, and consequently produces a flow ot vapor and/or liquid through the reservoir outlet into ythe superheater, and a iiow of vapor through the valved outlet is maintained in response to the demand signal.

The invention possesses other advantageous features, some of which, with the foregoing, will be set forth at length in the following description where those forms ot the invention which have been selected for illustration in the drawings accompanying and forming a part of the present specilications are outlined in full. In said drawings, several forms of the invention are shown, but it is to be understood that it is not limited to such forms, since the invention as set-forth in the claims may be embodied in other forms.

Referring to the drawings:

FIG. 1 is a schematic drawing of a vapor-generator of the character above described embodying the objects of our invention.

FIG. 2 is a typical pressure-enthalpy chart indicating the manner in whichr the generator illustrate-d in FIG. l operates to generate vapor at a constant pressure.

, FIG. 3 is a schematic drawing of a modification o the generator illustrated in FlG. l.

FIG. 4 is a schematic drawing illustrating an alternative way of operating the generator shown in FIG. 3.

More specifically, and as illustrated in FIG. l, thev y objects of our invention have been embodied in a system including a closed reservoir generally designated by the reference numeral l. communicating through a restricted connector 2 with an evaporator-superheater generally designated by the reference numeral 3. Preferably, this entire system is thermally shielded as at 4. Although ycertain limitations are placed on the size of connector 2, it need not be of capillary dimensions, for, as will presently more fully appear, the action of our generator does not depend upon capillary forces to produce iluid movement.

Located within the reservoir is a heat-generator here illustrated as an electrical heater 5 connected through external leads 6 and '7 with a temperature-controller 8.

Mounted within the evaporator-superheater 3 is a heat-generator here illustrated as an electric heater 9 communicating through external leads l1 and l2 with the temperature-controller S. The temperature-controller 8 senses the temperature in the reservoir 1 through a line 19 and the temperature in the evaporator-superheater 3 through a line lilla. Although not shown, there is associated with the temperature-controller S, the reservoir l, and the evaporator-superheater 3, means for sensing the temperatures in the two latter components so as to enable the temperature-controller 8 to maintain the temperature in the evaporator-superheater 3 at a higher value than the temperature within the reservoir l.

Disposed within the evaporator-superheater 3 is a maze 13 forming a tortuous path through which any iluid in the superheater is constrained to travel thereby to effect a better heat exchange between such fluid and the heater 9.

Communicating with the superheater 3 is an outlet 1d which, if desired, may be connected, by way of example, with the intake of the jet orice of attitude deviation correction motor not shown. Connected in the outlet ill is a motor-actuated valve 15 which, again for purposes of illustration, may be under the control of an attitude-sensor (not shown) through a line lo.

Contained within the reservoir l is a body 1'7 of iluid which, as indicated by the line 1S, may be partially in its liquid phase and partially in its vapor phase, these phases being in equilibrium with each other.

Although, as previously stated, the restricted connector 2 need not be of capillary dimensions, its dimensions should be such that the rate of ow of fluid therethrough from the reservoir 1 to the evaporator-superheater 3 will not exceed the rate at which the latter is able to evaporate the liquid content of tluid entering it.

Also, as previously indicated, the temperature-controller 3 is arranged to maintain the temperature within the evaporator-superheater 3 at a higher value than the temperature within the reservoir 1 to just insure that all of the uid entering the former will be converted into its vapor or gaseous phase. However, since the reservoir l and the evaporator-superheater 3 are continuously interconnected by passageway 2the pressure within the evaporator-superheater 3 is nevertheless equal to the pressure within the reservoir l, provided the valve l5 remains closed.

Now referring to FlG. 2, wherein the points A and B represent the conditions of the fluid in reservoir 1 and at the outlet 14 with the valve 15 closed. Liquid at A is at its saturation temperature and pressure, and the vapor at the outlet 1li is at substantially the same pressure, although at a higher temperature. The characteristics of two-phase liquid-vapor systems are such that, at any given pressure, liquid can exist in equilibrium with its own vapor at only one temperature. The imposition of a higher temperature in the evaporator-superheater 3 therefore assures that only dry vapor will be present therein.

When the valve l5 opens in response to a demand signal and vapor is discharged therethrough, the pressure in the system will tend to drop in accordance with Boyles law (PI/:K where the temperature remains constant) and consequently additional liquid in the reservoir l will be converted to vapor. Since the specific volume of a Vapor is much greater than `that of its liquid, the resulting additional evaporation in the reservoir 1 will increase the total volume of fluid therein, some of which will flow I through the connector v 2 into the evaporator-superheater 3 and thus equalize 'the'in'ternal pressures Within the system. All this'is indicated in FiG. 2 by thehorizontal lineA-B, it of course beinghere assumed that the tern# perature-controller 8 is arranged to maintain'the required Y temperature Within the reservoir .1f relative/to the tem-y perature Within-thesuperheater' 3 or, in other Words, to

replace the heat carried from the reservoir either as sensible heat or latent heat of `the fluid entering the superheater. Either liquid or vapor, or a mixture thereof, maybe discharged from the reservoir with equivalent results, since the` condition-of the fiuid leaving the outlet 14 will be vapor in either case. Y

A variety of liquids can be used for this purpose, such' as for example water, propane and ammonia. Also,Y

is the saturation pressure of ammonia at 105 F. The

fluid in the chamber 2l Will be entirelyliquid, since the prevailing pressure of 229 p.s.i.a. is greater than the saturation pressure of the propaneat 105 F. (200 p.s.i.'a.). Upon' opening the"valve ll-5', for vvapor discharge, the

'events taking piace in this Ysystem-Will parallel those taking place inExarnple l, except that all fluid leaving the chamber 21willbeliquid. Y K l Example3.ffWater-vapori-pressurized water 'Y *vapor-generator Y` n. This example is illustrated' in FIG. A4 whereiny it will l be seen that, vin so far as structure is, concerned, it is chemical heaters can be used instead of electrical heaters.

'Through proper design of Vthe fluid flowy andrthermal characteristics of the system, and WithoutA relative move- Y mentsV of internal parts, the generator system Vabove de-V scribed rnay be operated Without regard to the presence or direction ofV gravitational forces to prevent the escape of liquid'from the generator, While supplying dry'vapor for any requirement. l Y

Now referring to the modification Villustrated in FIG.

3.V With one exception,this modification is identical with i Vthe modification shown in FIG. 1, and consequently its the primes of surizing chamber 25 x containing a body 26 ofammonia. Example.LSelffpressurized propane vapor generator Now referring backA to FlGfl: Assume the propellant reservoir Vto be maintained at al temperature of 110,5 F.

. and the evaporator-superheater-jto'-bekept at 120311?.

Then with a propellant chargev Whose liquid volume is less than the volume of thereservoir 1x, attainment of thermal equilibrium conditions jwill'result in all liquid residing in the reservoir 1-,and the'pressure in the reser Yvoir will bethesaturation pressure'of propane attrlO5 F. or 200 p.s.i).a Because the reservoir Land. the evapof.v

ratersuperheater 3 are interconnected,'pressure in the latter will also bevr200Y p.s.i.a., but since kits temperature' is higher than thesaturation temperature at the prevailing," pressure, the vapor in the evaporator-superheater VWillbe superheated Operation `of they valve 15 Vto connect( to a resign Qf IQWsr; Pres.-` if sure will result in flow ofvapor from the evaporator-H superheater, with.l consequent lovyeringof pressuretherein. l-ressureinithe reservoir-*Twill also tendt'o decrease, 1 f

the evaporator-superheater v3 andiadditionalliquid. will bev vaporized in the reservoir to restore equilibrium, A volume of ifluid (either-.vapori orfliquid orboth) equal to the-volume off'vapo hlls.

producedlvvillkfiow tou/ard the evaporator-superheatei- 3-M tobecorneV d ry superheated vapor at 120 F., frornvvrhereYK it will proceed through thelevaporatorsuperheater,.to theidenticaljwith that illustrated in FIG. 3. For that' reason the corresponding elements have been indicated by identical reference numerals; Howeverfhere thepres-` sure Vchamber 25 contains a body 26. of water and water vapor, and Water y,is also used as the propellant in the expansible chamber 21. Heating of the chambers 21l and 25 is so arranged that When the system is noti'n thermal'equilibrium, that is, 25 is hotterthan 21,.heat may pass from 25 to 21.A n Now assume that 21-and 25 are maintained at 265" F. and that 3 is maintained to 280 F. The system equilibrium. pressure will be 381/2 i p.s.i.a. (saturation vaporpressureof water yat 265 F.),

which will allow thrust nozzles `connected to 14' to, operate supersonically underV normal katmospheric conditions. While theV control valve 15' is closed, 21 may contain bothV liquid and-vapor as in the case of Example-l..

When'the valve 15 is open andvapor isr discharged,` fluid moving from 21` to 3 may initially be liquid or vapor or both, as in the case of Example 1. l Continuous operation will at some tirneresult in a drop in temperature in '21 below thevtemperature yin 25. Atl this time, vapor in 21 Willbe transformed to liquid, since it will be subjected'tov the pressure of v25, greater than its vovvn `'saturation pres-v sure. Therefore, during this rcontinued operation, conditions in' this system willr correspond Vdirectly to the C011-,

ditions described `with reference V to, Example 2.

YThe principal advantage of the system shown in FIGS. Snand 4 overV 'andaboye advantages of the system shown in FIG, lgis that they have greater stability of )pferation during continuous vapor'dernanisinee 'the `site of vaporiy y Vzation of the. liquid is more Vclearly established, .This is particularly true withr respectfsto the second example. Temperature controls and` heating device arey less subjectV to random cycling, and reliability is vtherefore higher.

'1. A vapor-'generator for space vehicles f comprising:`

a first sealed/chamber providedgwith a vapor plenum,

meansKV fluidly-comrnunicating to ,the interior of `said first` chamber consisting ofa single connector connectedthere# to,"*afsecond fsealedg chamber, said connector; beingy 'permanently restrictedfandfconnected. to said secondf chamber, eachf ofzsaid chambers' containing a quantityof chemically identical .uids, Vsai'dgsecond ichamber being. lprovided with a valved outle t;` means for maintaining ther 'f luid Vcontent of said second chamberfat a temperature higher than the temperatureD of the Vluidcontfent of said `first chamber andat a temperature above the boiling point of the fluid content of said secondfchamber at the existing equilibrium'ipressure` of said first. andl secondJ chambers',I and means operable` uponthe opening of saidj outlet vfor.maintaining` the fi'urid in Ysaid first chamber esoutlet. These events will continue 1as-longasthe valvel isopen or untilthe reservoir 1 is emptied.

lxaimvle 2.-Ammona-pressurized propane vapor-generator Now assume that theammoniaf26 is in two-phase:v

equilibrium and that the expansiblechambe'r contains'- propane, that the chamberZS -isa maintained atl 105 AF'.-

and that the'v evaporator-superheater ismaintained at 1Z0 i" F. The system pressurewill now be 222 p.s .i.a.r, 'which sentially. at said equilibrium temperature and' pressure.,

l2.,.A vaporfgenerator for spacevehiclescomprisingfa first.sealedchamber'provided withfa vapor plenum, means` fiuidly- Ycommu,r'iicfating to .the interior of said ,firstI char'n-4 berncc/nsistingv of a single connector.. connected thereto', a f

second sealed" chamber, said connector. being permanently restricted. and connectedfto said Vsecond chamber,Y 'each of said* chambers containing a quantity ofI chemically identical fluids, said vsecond `chamber being providedlwithYa valved outlet; meansl for maintainingrthe fluidscontent of said second chamber lat. a temperature higher thanthe temperatures of the tluid content of said first chamber and at a temperature above the boiling point of the fluid content of said second chamber at the existing equilibrium pressure of said rst and second chambers; and means operable upon the opening of said outlet to replenish the heat content of the liquid in said first chamber so as to maintain the pressure of the vapor discharged from said outlet at a constant pressure.

3. A generator of the character set forth in claim l wherein the uid flow capacity of said restricted connector is such that under operating conditions iluid will flow therethrough from said first chamber to said second chamber at a rate not greater than the liquid content thereof can be evaporated in said second chamber when said outlet is open.

4. A vapor-generator of the character set forth in claim i l wherein said iirst chamber is in the form of an ex- ,varying the volume of said expansible chamber.

5. A vapor-generator of the character set forth in claim 4 wherein said expansible chamber is surrounded by a pressure chamber and `wherein means is provided for varying the pressure within said pressure chamber.

6. A vapor-generator of the character set forth in claim 1 including a temperature controller operating in response to variations in the temperatures within said rst and second chambers for maintaining said temperatures at substantially predetermined values.

References Cited in the le of this patent UNITED STATES PATENTS Re. 24,918 Mills Jan. 3, 1961 2,846,054 Rowand June 24, 1958 FOREIGN PATENTS 339,126 Great Britain Dec. 4, 1930 PERCY L. PATRTCK, Primary Examiner.

FREDERCK L. MATTESON. IR.. Examiner. 

1. A VAPOR-GENERATOR FOR SPACE VEHICLES COMPRISING: A FIRST SEALED CHAMBER PROVIDED WITH A VAPOR PLENUM, MEANS FLUIDLY COMMUNICATING TO THE INTERIOR OF SAID FIRST CHAMBER CONSISTING OF A SINGLE CONNECTOR CONNECTED THERETO, A SECOND SEALED CHAMBER, SAID CONNECTOR BEING PERMANENTLY RESTRICTED AND CONNECTED TO SAID SECOND CHAMBER, EACH OF SAID CHAMBERS CONTAINING A QUANITTY OF CHEMICALLY IDENTICAL FLUIDS, SAID SECOND CHAMBER BEING PROVIDED WITH A VALVED OUTLET; MEANS FOR MAINTAINING THE FLUID CONTENT OF SAID SECOND CHAMBER AT A TEMPERATURE HIGHER THAN THE TEMPERATURE OF THE FLUID CONTENT OF SAID FIRST CHAMBER AND AT A TEMPERATURE ABOVE THE BOILING POINT OF THE FLUID CONTENT OF SAID SECOND CHAMBER AT THE EXISTING EQUILIBRIUM PRESSURE OF SAID FIRST AND SECOND CHAMBERS; AND MEANS OPERABLE UPON THE OPENING OF SAID OUTLET FOR MAINTAINING THE FLUID IN SAID FIRST CHAMBER ESSENTIALLY AT SAID EQUILIBRIUM TEMPERATURE AND PRESSURE. 